With the quick development of computer technologies, there appear many information processing devices for accepting users' handwriting input with a handwriting recognition subsystem, such as personal digital assistants PDA or hand portable computers HPC. A handwriting recognition subsystem usually are usefully in the environment of inputting texts into a small mobile device like PDA, or inputting hard-to-enter characters like Chinese to a computer. Users can input handwritten data and symbols into computers by means of pen-like devices. Correspondingly, there appear many handwritten characters recognition devices, which can recognize a user's handwriting input.
In the field of handwriting input, two approaches to handwriting character recognition are known as on-line character recognition (OLCR) and optical character recognition (OCR). The OCR approach is sometimes also referred to as off-line handwriting recognition. In general, the on-line character recognition (OLCR) technique employs dynamic handwriting information, while the off-line handwriting recognition employs static handwriting information. All OCR systems generally use an input device, such as an optical scanner, for reading text from existing documents into a computer as an image file, process the image file by data perceiving and data re-construction (e.g. analyze the patterns and identify the characters they represent) to produce a text file for editing or other use later. Relative to the OLCR technique, as the OCR technique cannot obtain real-time dynamic handwriting information such as stroke direction, stroke order, pen tip pressure or speed etc as features, the recognition rate will be affected.
The OLCR technique uses a stylus as a handwriting input device to write characters each by each on a digitizing tablet, and then recognizes these characters by a recognition software. As OLCR technique employs dynamic handwriting information, such as stroke direction, stroke order, tip pressure or speed etc as features, it provides generally better recognition accuracy, and is used widely for current handwriting input devices.
At present, conventional handwriting input devices utilizing OLCR technique usually request a touch sensitive pad which incorporates either magnetic sensor or pressure sensor to sense and record the pen strokes that are touching on the pads surface, e.g. digitizing tablet. The conventional digitizing tablet usually has a wire connecting an external smart stylus.
The IBM's ThinkScribe is a device integrating a handwriting digitizer having a digitizing tablet with a traditional paper-based recording system. The digitizing tablet includes an active area capable of receiving electromagnetic signals from a radio frequency coupled stylus. This device records a user's handwriting input in strokes and associated timing and can reproduce the user's handwriting input according to the original timing information. A user may write the documents to be transmitted on the digitizing tablet or paper. The digitizing tablet generates a data flow representative of strokes and the associated events, and records the data flow in a nonvolatile memory. The associated events in the data flow may be generally categorized as being either automatically generated by the input device or as being user invoked. Automatically generated events are events which occur and are detected and recorded without specific input from the user. For example, there may be defined a pen-down event which indicates that the stylus was brought into contact with the writing surface and a pen-up event which indicates that the stylus was lifted from the writing surface. A “ink trace” may thus be defined as a series of pen coordinates recorded between a pen-down and a pen-up event.
All the input devices mentioned above require a touch sensitive pad which incorporates either magnetic sensor or pressure sensor to sense and record the pen strokes that are touching on the pads surface. The pad is additional cost to an existing PDA or a personal computer. The pad is also large in size which either is difficult to carry, or it occupies the screen area when it is built onto a PDA and in operation. The pad usually has a wire connecting the pad to the computer, and a wire connecting the pen to the pad. The situation sometimes is a mess.
In other types of recognition systems, a pure digital camera input may be used for the sake of recognition, however, the processing and results may not be as precise.
As many computer systems (e.g. notebook PC, pervasive device, PDA etc.) are increasingly entering market equipped with an embedded digital camera of relatively high resolution, it would be advantageous to provide digital video data with the digital camera for use in the handwriting recognition process in such pervasive device. Accordingly, there is a need to provide a easier and a low cost solution which enables an user to write on a paper without a touch sensor and a wire connecting the sensor to a computer (or a pervasive device and the like) and a wire connecting a stylus (or a pen) to the sensor, but equipped with a low cost digital camera functioning to overcome the known drawbacks mentioned above.